Support for insulator



Oct. 4, 1932. E. BURKE ,88

SUPPORT FOR INSULATORS Filed May 11. 1929 I $206722? M jyiizzazd fi/Iif Patented Oct 4, 1932 UNITED STATES PATENT OFFICE EDMUND BURKE, 0F PORTLAND, MAINE, ASSIGNOR TO BROWN COMPANY, OF BERLIN, NEW HAMPSHIRE, A CORPORATION OF MAINE SUPPORT FOR INSULATOR Application filed May 11,

This invention relates to a support for an electric insulator capable of being mounted on a cross arm of a wire-carrying pole, or on any other suitable supporting means. Heretofore wooden or metal insulator supports have been in common use, these supports having comparatively no resiliency, thus causing breakageof porcelain insulators. For high tension lines, especially where the wires are strung between widely spaced poles or towers, wooden insulator supports do not have suflicient strength for the stresses imposed on them. On the other hand, iron or steel pins for the insulators are objectionable on account of their high electric conductivity. When an insulator is supported directly by an iron pin and becomes cracked, moisture thereon as from rain will cause a short circuit through the supporting pin. Moreover, metal pins shaped to receive high tension insulators are massive and heavy, so that they add materially to the total load carried by the poles. According to the invention, I provide an insulator support which is substantially as strong as the metal pin, which is considerably lighter in weight, and which in itself possesses electric insulating qualities of a high degree. My improved insulator support, as hereinafter described, may consist essentially of a metal pin to provide strength for the structure, and a waterproofed fiber skirt mounted on the pin and shaped to receive an insulator thereon. The fiber skirt may be readily molded or otherwise formed and may be rendered waterproof by a mixture of Waterproofing material with the fibrous material prior to the molding step, or by first molding the skirt of fibrous material and then saturating the molded skirt with waterproofing compound.

For a more complete disclosure of the invention, reference may be had to the description thereof which follows and to the drawing, of which,

Figure 1 represents an embodiment of the invention in side elevation.

Figure 2 is a section on the line 22 of Figure 1.

Figure 3 is a section on the line 8-3 of Figure 2.

1929. Serial No. 362,207.

Figure 4 is a section on the line H of Figure 2.

The support may consist of a fiber skirt 10 which, as shown in Figure 2, may be screw threaded or otherwise mounted on the upper end of an upright pin 11. This pin is preferably of sufiicient length to extend downwardly below the bottom of the skirt 10 a sufiicient distance to pass into or through a supporting arm 12. As shown, the pin 11 is provided with a shoulder 13 adapted to engage the upper surface of the arm 12, a nut 14 being threaded to the lower end of the pin so as to engage the lower face of the arm 12. The pin 11 is arranged to extend upwardly into the insulator (not shown) thus providing a rigid element for the insulator support. As shown in Figure 2 a portion of the pin 11 may be threaded as at 15 to receive the skirt 10 in threaded engagement. Above this threaded portion may be a reduced portion 16 which, as shown, is adapted to extend upwardly into a head portion 17 of the skirt 10. This head portion may be screw threaded as at 18 to receive an electric insulator in threaded engagement in a manner well known in the art. The portion 16 of the pin 11 which extends upwardly within the head 17 is preferably reduced in order to provide an ample thickness of fibrous material between the metal of the pin and the glass or porcelain of the insulator mounted on the head 17. This fibrous material acts as a cushion between the insulator and the pin so as to avoid fracture of the insulator which might otherwise result from unequal thermal expansion of the pin and insulator.

In order to avoid deterioration of the skirt 1O bythe action of atmospheric moisture, and to serve as a secondary electric insulating element, the skirt 10 is preferably impregnated with a waterproofing substance which is likewise an electric non-conductor. Such substances may include asphalt, tar, pitch, sulphur or equivalent materials. In making the skirt 10, such waterproofing and insulating material may be introduced into the fibrous material of which the skirt is made before the skirt is molded. If the skirt is molded of wet pulp, such waterproofing material may conveniently be intermixed in the form of an aqueous emulsion well known in the art. Such emulsions of asphalt or similar sub stances maintain the colloidal particles of asphalt separate as long as the emulsion is wet, and these particles coalesce when the aqueous vehicle dries out, so that'a continuous body of waterproof asphalt may thus result. If preferred, the fibrous material may be mixed with a. molten waterproofing material or with a dissolved waterproofingmaterial prior to the molding step. If preferred, the skirt may be molded or otherwise formed of fiber, the molded article being subsequentlysaturated with waterproofing material byimmersingthe article in molten asphalt, pitch or the like, or soaking the article in a. solution of Waterproofing substance. 7

In order to provide-further protection for the skirt, it is preferably dipped in a bath of comparatively viscous coating material so as to cover its exterior surface and preferably a portion of its interior surface with a substantial layer of waterproofing material, such, for example, as asphalt having a relatively high melting point. As the head portion 17 of the skirt is enclosed in and fully protected by the insulator which fits over it, it is not necessary that such coating be extended over the head. The exterior and interior threads of the skirt may be formed in any desired way. They may, for example, be formed in the process of molding the skirt as a whole, with or without a further step of finishing the threads by a cutting or an abrading operation. The skirt is preferably secured firmly on the pin 11. This may be accomplished by screw threading a portion of the inner surface of the skirt as at 19 to receivethe threaded portion 15 of the pin. 1 In addition to this, cement may also be used to hold thetwoparts together more securely. In making the skirt 10 the thread 19 may be formed in the mold and subsequently coated partly or wholly with the same material which is used to coat the exterior surface of the skirt. 7 For this purpose a thermoplastic waterproofing material, such as asphalt, may be used. When the pin 11 is inserted Within the skirt 10 in screw threaded engagement with the thread 19,.it may be sufficiently heated to soften the thermoplastic coating on the threads 19. After the pin has thus been inserted, the asphaltic coating 011 the threads 19 thereupon cools and sets, thus firmly cementing the skirt on the p1n.

As shown in Figure 2, the lower portion 22 of the skirt may be shaped to diverge downwardly from the shank of the pin 11 so as to increase the efficiency of the skirt as an auxiliary insulator by being spaced at its lower portion from the pin 11 and by keeping the adjacent portion of the pin dry.

An embodiment of this invention having thus been described, it should be evident to those skilled in the art that various changes and modifications might be made therein without departing from its spirit or scope as defined by the appended claim.

I claim:

A support for an electric insulator, comprising a metalpin having a reduced upper portion and a threaded portion immediately below said reduced portion, and a molded waterproofed fibrous skirt fitting on said reduced and threaded ortions of'the pin and diverging downward yfrom the portion of the pinbelow said threaded portion, said skirt having an'external thread opposite the reduced portion of the pin therein and a thicker wall below said external thread surrounding the threaded portion of the pin.

In'testimony whereof I have aflixed my signature.

EDMUND BURKE. 

